Perhaps you should try some spelling variations:
accident research » current research, recent research
vaccine research » medicine research
active vaccine » anti vaccine, positive vaccine
post accident » post incident, plant accident, road accident
july 2009 » july 2008, july 2007, july 2019
july 2006 » july 2008, july 2007, july 2013

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (( active vaccine research : july 2009 ) or ( post accident research : july 2006 ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( active vaccine research : july 2009 ) OR ( post accident research : july 2006 )).
• Adding a wildcard symbol may retrieve word variants: (( active vaccine research : july 2009 ) or ( post accident research : july 2006 ))*.